This pic is made for my work project in renewable power sources.
Rather rough, but my working pc is a dinosaur’s age and AAO render was more than 45 mins :mad:
Some details of interior were rendered separetly and added in GIMP.
Seems like quite fine work ;).
45 minutes does sound like quite a lot. Have you considered lighting it
with different means than AAO? (read: lamps only).
I think the most apparent flaw right now is how clean everything is.
You should spend some time on your materials, and add more variation
to the surfaces. A few bumps and a little dirt around the edges can add
quite a lot to an image.The new projection painting makes it very easy to paint new textures. You should also make the windows transparent 
This depends, of course, what you are trying to achieve? If you are using this
strictly for illustrative purposes i think it is quite fine.
TobiasDN
Thank you for your reply.
Actually it was a 1,5 hour job to illustrate how equipment to be placed and to show approximate scale of objects.
I don’t use AO anymore for this scene - too much time to render, but if I make textures for bumb, dirt, etc - then I will bake AO.
I was using array and mirror modifiers a lot, so I will be have to apply them before texturing - and it looks like a lot of work forehead.